#define _CRT_SECURE_NO_WARNINGS 1

#include "snake.h"

void SetPos(int x, int y)
{
	//获得设备句柄
	HANDLE handle = GetStdHandle(STD_OUTPUT_HANDLE);
	//根据句柄设置光标的位置
	COORD pos = { x, y };
	SetConsoleCursorPosition(handle, pos);
}

void WelcomeToGame()
{
	//欢迎信息
	SetPos(35, 10);
	printf("欢迎来到贪吃蛇小游戏\n");
	SetPos(38, 20);
	system("pause");
	system("cls");

	//功能介绍信息
	SetPos(15, 10);
	printf("用 ↑ . ↓ . ← . → 来控制蛇的移动，F3是加速，F4是减速\n");
	SetPos(15, 11);
	printf("加速能得到更高的分数");
	SetPos(38, 20);
	system("pause");
	system("cls");
}

void CreateMap()
{
	int i = 0;
	//上
	SetPos(0, 0);

	for (i = 0; i <= 56; i += 2)
	{
		wprintf(L"%lc", WALL);
	}

	//下
	SetPos(0, 26);

	for (i = 0; i <= 56; i += 2)
	{
		wprintf(L"%lc", WALL);
	}

	//左
	for (i = 1; i <= 25; i++)
	{
		SetPos(0, i);
		wprintf(L"%lc", WALL);
	}

	//右
	for (i = 1; i <= 25; i++)
	{
		SetPos(56, i);
		wprintf(L"%lc", WALL);
	}
}

void InitSnake(pSnake ps)
{
	//创建5个蛇身的结点
	pSnakeNode cur = NULL;
	int i = 0;

	for (i = 0; i < 5; i++)
	{
		cur = (pSnakeNode)malloc(sizeof(SnakeNode));
		
		if (NULL == cur)
		{
			perror("InitSnake():malloc()");
			return;
		}

		cur->x = POS_X + 2 * i;
		cur->y = POS_Y;
		cur->next = NULL;

		//头插法
		if (NULL == ps->pSnake)
		{
			ps->pSnake = cur;
		}
		else
		{
			cur->next = ps->pSnake;
			ps->pSnake = cur;
		}
	}

	//打印蛇身
	while (cur)
	{
		SetPos(cur->x, cur->y);
		wprintf(L"%lc", BODY);
		cur = cur->next;
	}

	//贪吃蛇的其他信息初始化
	ps->dir = RIGHT;
	ps->FoodWeight = 10;
	ps->pFood = NULL;
	ps->Score = 0;
	ps->SleepTime = 200;
	ps->status = OK;
}

void CreateFood(pSnake ps)
{
	int x = 0;
	int y = 0;

again:
	do
	{
		x = rand() % 53 + 2;
		y = rand() % 24 + 1;
	} while (x % 2 != 0);

	//坐标和蛇的身体的每个节点的坐标比较
	pSnakeNode cur = ps->pSnake;

	while (cur)
	{
		if (x == cur->x && y == cur->y)
		{
			goto again;
		}

		cur = cur->next;
	}

	//创建食物
	pSnakeNode pFood = (pSnakeNode)malloc(sizeof(SnakeNode));
	
	if (NULL == pFood)
	{
		perror("CreatFood():malloc()");
		return;
	}

	pFood->x = x;
	pFood->y = y;
	pFood->next = NULL;

	ps->pFood = pFood;
	SetPos(x, y);
	wprintf(L"%lc", FOOD);
}

void GameStart(pSnake ps)
{
	//设置控制台的信息，窗口大小，窗口名
	system("mode con cols=100 lines=30");
	system("title 贪吃蛇");

	//隐藏光标
	HANDLE handle = GetStdHandle(STD_OUTPUT_HANDLE);
	CONSOLE_CURSOR_INFO CursorInfo;
	GetConsoleCursorInfo(handle, &CursorInfo);//获取控制台光标信息
	CursorInfo.bVisible = false;
	SetConsoleCursorInfo(handle, &CursorInfo);
	
	//打印欢迎信息
	WelcomeToGame();

	//绘制地图
	CreateMap();
	
	//初始化蛇
	InitSnake(ps);
	
	//创建食物
	CreateFood(ps);
}

void PrintHelpInfo()
{
	SetPos(62, 15);
	printf("1.不能穿墙，不能咬到自己");
	SetPos(62, 16);
	printf("2.用 ↑.↓.←.→ 来控制蛇的移动");
	SetPos(62, 17);
	printf("3.F3是加速，F4是减速");
	SetPos(62, 18);
	printf("4.ESC：退出游戏 space：暂停游戏");
}

void pause()
{
	while (1)
	{
		Sleep(100);
		
		if (KEY_PRESS(VK_SPACE))
		{
			break;
		}
	}
}

int NextIsFood(pSnake ps, pSnakeNode pNext)
{
	if (ps->pFood->x == pNext->x && ps->pFood->y == pNext->y)
	{
		return 1;//下一个坐标处是食物
	}
	else
	{
		return 0;
	}
}

void EatFood(pSnake ps, pSnakeNode pNext)
{
	pNext->next = ps->pSnake;
	ps->pSnake = pNext;

	//打印蛇
	pSnakeNode cur = ps->pSnake;

	while (cur)
	{
		SetPos(cur->x, cur->y);
		wprintf(L"%lc", BODY);
		cur = cur->next;
	}

	ps->Score += ps->FoodWeight;

	//释放旧的食物
	free(ps->pFood);
	ps->pFood = NULL;

	//新建食物
	CreateFood(ps);
}

void NotEatFood(pSnake ps, pSnakeNode pNext)
{
	//头插法
	pNext->next = ps->pSnake;
	ps->pSnake = pNext;

	//释放尾结点
	pSnakeNode cur = ps->pSnake;

	while (cur->next->next)
	{
		SetPos(cur->x, cur->y);
		wprintf(L"%lc", BODY);
		cur = cur->next;
	}

	SetPos(cur->x, cur->y);
	wprintf(L"%lc", BODY);

	//将尾节点的位置打印成空白字符
	SetPos(cur->next->x, cur->next->y);
	printf("  ");

	free(cur->next);
	cur->next = NULL;
}

void KillByWall(pSnake ps)
{
	if (0 == ps->pSnake->x ||
		56 == ps->pSnake->x ||
		0 == ps->pSnake->y ||
		26 == ps->pSnake->y)
	{
		ps->status = KILL_BY_WALL;
	}
}

void KillBySelf(pSnake ps)
{
	pSnakeNode cur = ps->pSnake->next;//从第二个节点开始

	while (cur)
	{
		if (cur->x == ps->pSnake->x && cur->y == ps->pSnake->y)
		{
			ps->status = KILL_BY_SELF;
			return;
		}

		cur = cur->next;
	}
}

void SnakeMove(pSnake ps)
{
	pSnakeNode pNext = (pSnakeNode)malloc(sizeof(SnakeNode));
	
	if (NULL == pNext)
	{
		perror("SnakeMove()::malloc()");
		return;
	}

	pNext->next = NULL;

	switch (ps->dir)
	{
	case UP:
		pNext->x = ps->pSnake->x;
		pNext->y = ps->pSnake->y - 1;
		break;
	case DOWN:
		pNext->x = ps->pSnake->x;
		pNext->y = ps->pSnake->y + 1;
		break;
	case LEFT:
		pNext->x = ps->pSnake->x - 2;
		pNext->y = ps->pSnake->y;
		break;
	case RIGHT:
		pNext->x = ps->pSnake->x + 2;
		pNext->y = ps->pSnake->y;
		break;
	}

	//下一个坐标处是否是食物
	if (NextIsFood(ps, pNext))
	{
		//是食物就吃掉
		EatFood(ps, pNext);
	}
	else
	{
		//不是食物就正常走一步
		NotEatFood(ps, pNext);
	}

	//检测撞墙
	KillByWall(ps);

	//检测撞到自己
	KillBySelf(ps);
}

void GameRun(pSnake ps)
{
	//打印帮助信息
	PrintHelpInfo();
	
	if (KEY_PRESS(VK_UP) || KEY_PRESS(VK_DOWN) ||
		KEY_PRESS(VK_LEFT) || KEY_PRESS(VK_RIGHT) ||
		KEY_PRESS(VK_ESCAPE) || KEY_PRESS(VK_SPACE) ||
		KEY_PRESS(VK_F3) || KEY_PRESS(VK_F4))
	{
		;//消除之前 按任意键继续 的影响，比如我按了空格然后进入了游戏，这里不检测，那么下面的代码会检测到我按过空格，游戏一开始就会暂停
	}

	do
	{
		//当前的分数情况
		SetPos(62, 10);
		printf("总分：%5d\n", ps->Score);
		SetPos(62, 11);
		printf("食物的分值：%02d\n", ps->FoodWeight);

		//检测按键
		//上、下、左、右、ESC、空格、F3、F4
		if (KEY_PRESS(VK_UP) && ps->dir != DOWN)
		{
			ps->dir = UP;
		}
		else if (KEY_PRESS(VK_DOWN) && ps->dir != UP)
		{
			ps->dir = DOWN;
		}
		else if (KEY_PRESS(VK_LEFT) && ps->dir != RIGHT)
		{
			ps->dir = LEFT;
		}
		else if (KEY_PRESS(VK_RIGHT) && ps->dir != LEFT)
		{
			ps->dir = RIGHT;
		}
		else if (KEY_PRESS(VK_ESCAPE))
		{
			ps->status = ESC;
			break;
		}
		else if (KEY_PRESS(VK_SPACE))
		{
			//游戏要暂停
			pause();//暂停和恢复暂停
		}
		else if (KEY_PRESS(VK_F3))
		{
			if (ps->SleepTime > 80)
			{
				ps->SleepTime -= 30;
				ps->FoodWeight += 2;
			}
		}
		else if (KEY_PRESS(VK_F4))
		{
			if (ps->FoodWeight > 2)
			{
				ps->SleepTime += 30;
				ps->FoodWeight -= 2;
			}
		}

		//走一步
		SnakeMove(ps);

		//睡眠一下
		Sleep(ps->SleepTime);

	} while (OK == ps->status);
}

void GameEnd(pSnake ps)
{
	SetPos(15, 12);

	switch (ps->status)
	{
	case ESC:
		printf("主动退出游戏，正常退出\n");
		break;
	case KILL_BY_WALL:
		printf("很遗憾，撞墙了，游戏结束\n");
		break;
	case KILL_BY_SELF:
		printf("很遗憾，咬到自己了，游戏结束\n");
		break;
	}

	//释放贪吃蛇的链表资源
	pSnakeNode cur = ps->pSnake;
	pSnakeNode del = NULL;

	while (cur)
	{
		del = cur;
		cur = cur->next;
		free(del);
		del = NULL;
	}

	free(ps->pFood);
	ps->pFood = NULL;

	ps  = NULL;
}